Astrology, the supposed influence of the stars on human events, is alluded to in the Hebrew Bible more than once. In Lev. 19:26 and Deut. 18:10 the Tora warns about idolatrous practices like theme'onen (=the seer of times). The prophets of Israel were also aware of this very popular pagan practice among the Babylonians and virtually all other ancient civilizations, and they scoffed at the "star-gazers" or hobere ha-shamayim, "The readers of heavens". Isa. 47:13 and Jer. 10:2.
In the Talmud astrology is called itstagninut. This is also the term used by Maimonides in Mishne Tora. In Hilkhot 'aboda zara 11:8 he writes: "Who should be considered a me'onen? The one that predicts the times, saying through astrology (itstagninut) such-and-such a day will be a good day... or a bad day, such-and-such a day will be auspicious for performing this task, and such-and-such a day will be bad for doing that task, etc." It is forbidden by the Tora, as part of the prohibitions against idolatrous practices, to tell fortunes, to seek astrologers or fortunetellers and even worse, to act upon an astrological sign or warning.
To clarify even further Maimonides' position on this matter I'm quoting his words in Perush haMishnayot, 'aboda zara, 4:9: "Astrology... is not as some people believe, a credible science which the Tora wished to forbid. It is a nonsensical superstition... by which people attribute to the stars imaginary powers... [astrology] together with witchcraft, demonology, incantations, divination and summoning the spirits of the dead represent the essence of idolatry ('aboda zara)".
Upon being asked by the rabbis of southern France whether it was possible to combine astrology with Judaism Maimonides replied that he had explored the principles of astrology and concluded that "[astrology]... is no science at all, but mere foolery and superstition ... I well know that you may seek and find in the Talmud and Midrashim isolated sayings implying that the stars at the time of a man's birth will have a certain effect upon him... but this need not perplex you". The supposition that the fate of a man could be dependent upon the constellations was ridiculed by him. He argued, furthermore, that such theories were devised to rob life of purpose and to make people dependent on the whims of the readers of heaven.
